Attention please! This is not the work of a native speaker, please have a look at the preview to decide if my English matches your standards. Thank you.
Actually, this Pay-what-you-want-title is Mr. Kowolski his fault (although he had no hand in it, I am not affiliated with him and I -bet- he does not even know of my existence): in his Going Through Forbidden Worlds, Zzarchov Kowolski leaves it to the GM to create several demonic encounters for the adventure itself. For doing so he points to the Summon spell (LotFP Player Core Rules p. 134) and/or the Random Esoteric Creature Generator while also giving the advice that many of the creatures encountered may be influenced by a catholic´s vision of hell and the demonic.
I am not a catholic and I don´t own a copy of the Random Esoteric Creature Generator, but I am gifted with a queer creativity, a knack for handling an RPG´s rules and tables and, currently, a LOT of time at hand. So I did some brain storming, and crossed-bred the results with the tables of LotFP Summon spell for reference, further inspiration and right-sizing of a total of 10 demonic beings. Eight of them are HD:3, the last two are HD:6. You do not need Going Through Forbidden Worlds to make use of them, they will work in any other LotFP game as well. Oh, they are pay-what-you-want, too!
Have fun with them, and feel free to write a comment about how my creations fared in your game. Its is always nice to hear from “the children”.